Continuing advances in computers and digital communications have resulted in the proliferation of digital imagery, such images including, for example, still images, full motion video, graphics incorporated into on-line catalogs, advertisements and web pages. While substantial effort has been expended to ensure that data storage and transmission provides an accurate representation of the original data, fidelity of a rendered image with respect to the original or a desired image has been largely left to the individual user.
Prior techniques to ensure the fidelity of an output device such as a video monitor or color printer accurately represents a desired image relied heavily upon specialized devices such as CRT color analyzers, such as the Minolta CA-100 or the Sencore CPT 288 color analyzer. These devices may be capable of measuring the exact gain or gamma function relating display parameters to actual screen output. Such devices have typically been costly and relegated to manufacturing and other test facilities when the cost is justified. However, consumer and small scale usage has not been adequately addressed. This has become a problem with the ever increasing usage of images and graphics in which image fidelity is increasingly important.
At least one software manufacture includes in their game programs a method to calibrate screen video without a photometer or other equipment, instead using just the naked eye. According to this method, a square area is displayed on the screen and the brightness of the square is adjusted until it is just invisible. From this adjustment, an estimate is made of the black level of the screen and graphics are re-calibrated so that display presentation is optimized. However, this method is subjective and requires substantial user effort and experimentation.
Other approaches to calibrating an output device are described in U.S. Pat. Nos. 5,012,163 and 5,381,309 assigned in common with the present application and incorporated herein by reference in their entireties.
There is a need for a simplified method and an inexpensive apparatus for calibrating color rendition of an output device such as a video monitor or printer to ensure image fidelity and, in particular, maintain accurate and consistent color rendition of images.